Cozzone Curves- Where can they be found? 6

[realJedi]

Hello all,

I'm looking for Cozzone curves for use with the Fb=Fm+Fo(K-1) equation, but need more curves than is shown in Bruhn. Does anyone know where they can be found? And better yet are they online to be downloaded/copied?

Thanks for the help.....

 

[SuperStress]

What are you looking for specifically? Do you need more 'K' values or more values of f_o?

Are you trying to solve a particular problem, or are you just compiling reference data?

SuperStress

 

[realJedi]

Superstress,

I'm looking to compile reference data for values of Fo for solving problems with precipitation hardening stainless steels, ferritic and austenitic stainless steels. However what I'm really after are the values of Fb and need Fo to calculate.

My current need is to find a reference for 17-4PH at H900.


A little off topic but, similarly, I understand that Ramberg-Osgood curves yeild similar values for Fb without the need for values of Fo?

 

[SuperStress]

Here are the equations for f_o. I put these into a spreadsheet for quick calculations. This is a little complicated, but I think this will be comprehensible...

f_o/F_tu=6/e_u²*{1/3*(F_tu/E)²+e_u'*((m+1)/(m+2))*(F_tu/E)+(m/2m+1)*(e_u')²}-2

where:

m=log(e_u'/.002)/log(F_tu/F_ty)

and

e_u'=e_u-(F_tu/E)

Where:

e_u=elongation
E=Young's modulus
F_tu,F_ty are ultimate and yield values in tension.

In case that's not confusing enough, here are my spreadsheet entries; you should be able to cut-and-paste these into Excel and get an answer.

For this spreadsheet, the following variables are defined in these locations:

B2=E, Young's modulus
B3=F_tu, ultimate tensile strength
B4=e_u, elongation (e.g. 7%=.07)
B5=e_u'=B4-B3/B2
B6=F_ty, yield strength in tension
B7=m=LOG(B5/0.002)/LOG(B3/B6)
B8=f_o/F_tu=(6/(B4^2))*((B3/B2)^2/3+B5*(B7+1)/(B7+2)*B3/B2+(B7/(2*B7+1))*B5^2)-2
B9=f_o=B8*B3


That should work, if I've managed to transcribe it correctly. By the way, the reference for this is McDonnell Aircraft Report 339, 2 January 1969, Revised 1 December 1971, page 14.02.

Let me know if it doesn't work and I'll check my equations again to make sure I didn't fat-finger it.

SuperStress

 

[crackman]

Hi all

Regarding references for additional material curves for the Cozzone method, Lockheed employs this method in SMM 53d (SMM is the Structures Methods Manual) and published additional data for all their methods for each of the Mil Handbook versions in supplemental Lockheed Reports (ie LRXXXXX). The one I believe I have used in the past was called LR31445 entitled "Stress Memo Curves for Materials in Mil-Hdbk-5E". If you can borrow one from someone you will find addtional curves for plastic bending for: 2024,2090,2124,6061,7050,7075,7175,7475,7049,Ti6al4v,inconel,15-5ph,17-4ph,13-8ph,300m,A356,A357,etc. and for various product forms.

Good hunting

JB

 

[stseng]

Hi,

In Table C3.2 at page C3.11 of Bruhn's book, there is a fo value for Yield strengh.

I am wondering if there is a corresponding formula such as "fo/Ftu=6/eu2*{1/3*(Ftu/E)2+eu'*((m+1)/(m+2))*(Ftu/E)+(m/2m+1)*(eu')2}-2" for the yield strength?

Thank you.

laotseng